The photodiode arrays of this type conventionally known include back-illuminated photodiode arrays of a type in which light is incident through the opposite surface (back surface) to a surface where bump electrodes or the like are formed (e.g., reference is made to Patent Document 1). The photodiode array disclosed in this Patent Document 1 has photodiodes 140 of pn junctions made by forming p-layers 134 of prismatic shape in an n-type silicon substrate 133, as shown in FIGS. 26 and 27. A scintillator 131 is bonded through a negative electrode film 136 to the back surface (the upper side in the drawing) opposite to the surface where the photodiodes 140 are formed (the lower side in the drawing). When light resulting from wavelength conversion in the scintillator 131 is incident into the photodiodes 140, each of the photodiodes 140 generates an electric current according to the incident light. The electric current generated in each photodiode 140 is outputted through positive electrode 135 formed on the front surface side, solder ball 139, and solder pad 138 provided on printed circuit board 137.
Patent Document 1 Japanese Patent Application Laid-Open No. 7-333348